Cathode ray tube deflecting device



y 1939. 1. e. MALOFF 2,164,931

CATHODE RAY TUBE DEFLECTING DEVICE Filed Oct. 31, 1955 INVEN'I'OH i [awry GJfaZoff Witness:

Patented July 4, 1939 2,164,931

UNITED STATES PATENT OFFICE CATHODE RAY TUBE DEFLECTING DEVICE Ioury G. Maloff, Philadelphia, Pa... assignor to Radio Corporation of America, a corporation of Delaware Application October 31, 1935, Serial No. 47,556 7 Claims. (Cl. 250-457) My invention relates to deflecting means for the strength of the magnetic deflecting field is cathode ray tubes and particularly to electrofairly uniform whereby there is a reduction in magnetic deflecting means. defocusing of the cathode ray and in distortion In the past, electro-magnetic deflection has inof the scanning pattern. The uniformity of the volved two disadvantages; it caused a certain magnetic field may be improved by providing 5 amount of defocusing of the cathode ray, and projections H and [2 on the horizontal legs 1 and it caused the cathode ray to scan on the screen 8, respectively, as illustrated in Fig. 1. It should an area which had curved sides rather than be understood, however, that such projections straight sides. are not necessary for satisfactory operation of An object of my invention is to provide electrothe deflecting system. It may be noted that for 10 magnetic deflecting means which avoids, to a best operation the deflecting coils 2 and 3 are of marked extent, the above mentioned disadvansubstantially the same length as the vertical legs tages. of the core, that is, they should take up substan- A further object of my invention is to provide tially all the space available for deflecting coils.

a simplified deflecting structure which is cheap Referring to Fig. 2, the deflecting coil structure 15 to manufacture. described above is shown applied to a cathode In practicing my invention I provide a magray tube 9 of the type employing electrostatic netic core structure which may be either recfocusing of the cathode ray. The cathode ray tangular or round in shape. Deflection in one tube is of a well known type comprising a highly plane, vertical deflection for example, is accomevacuated envelope having therein an indirectly 20 plished by means of two coils wound on opposite heated cathode l3, a control grid [4, a first anode sides of the core and so electrically connected l6 and a second anode IT. The second anode ll that their magnetic fields buck. Another pair of consists of a metallic coating on the inner surcoils, also connected to produce bucking fields, face of the envelope and it functions both to acmay be mounted on the core for deflecting the celerate the electrons and to focus them to a 25 cathode ray vertically. small spot on a fluorescent screen l8 at the end.

Other objects, features and advantages of my of the tube. invention will appear from the following descrip- When a deflecting coil structure such as shown tion taken in connection with the accompanying in Fig. 1 is employed, if it is desired to deflect a drawing in which, cathode ray in a direction at right angles to the 0 Figure l is a View in perspective of deflecting deflection produced by the deflecting coils, such coil structure embodying my invention, deflection is preferably produced by electrostatic Fig. 2 is a view illustrating the structure shown deflecting plates. It is sometimes preferred in Fig. 1 applied to a well known form of cathode however, to obtain both vertical and horizontal ray tube, and deflection by means of deflecting coils. In that 35 Figs. 3 and 4 are views illustrating other emcase the embodiment of my invention illustrated bodiments of my invention. in Fig. 3 may be employed. This structure is sub- Referring to Fig. 1 this embodiment of my instantially. the same as that shown in Fig. 1 exvention comprises a closed magnetic core struccept that vertical deflecting coils l9 and 2i have ture l which is rectangular in shape. The core been mounted on the horizontal legs of a core 22. 40 preferably is built up of laminations of trans- The horizontal deflecting coils 23 and 24 are so former iron. Deflecting coils 2 and 3 for proconnected either in series or in parallel that their ducing horizontal deflection of a cathode ray are magnetic fields are in bucking relation as indimounted on the vertical legs 4 and 6 of the core. cated by the letters N and S. Thus the vertical These coils are so connected either in series or in deflecting coils l9 and 2| produce a north pole 45 parallel that the magnetic fields produced by the at the left hand vertical leg of the core and a two coils are in bucking relation as indicated by south p t t right hand v i al l of the the letters N and S on the drawing. core.

It will be seen that the lines of force leave the The horizontal deflecting coils 23 and 24 are upper horizontal leg 1 of the core and pass into likewise so connected that their magnetic fields 50 the lower horizontal leg 8 of the core as indicated buck to produce a north pole in the upper horiby the dotted lines. zontal leg of the core and a south pole at the The position of the cathode ray tube is indilower horizontal leg of the core. It will be uncated at 9 by the dotted circle. It will be apparderstood, of course, that the north and south ent that in the region of the cathode ray tube poles reverse their locations with the reversal of 55 current through the deflecting coils. As mentioned in connection with Fig. 1, the deflecting coils preferably occupy all the available space on the core legs. In order to illustrate the invention more clearly, considerable unused space on the core legs has been shown in Fig. 3.

It will be apparent that the sensitivity of the deflecting system shown in Fig. 3 is reduced by the fact that it is impossible to bring the legs of the core 22 close to the envelope of the cathode ray tube 9 due to the windings being located between the core and the envelope. This defect is largely overcome and the magnetic field is. made still more uniform by employing the arrangement shown in Fig. 4. In this embodiment of the invention each coil on a core leg is split and spaced apart whereby a projection may be provided on the leg between the two coil sections. The two coil sections are connected in series and the two series connected sections then connected with the remaining coils the same as in the embodiment illustrated in Fig. 3. For example, considering the horizontal deflecting coils, the right hand vertical leg 26 of the core has two coil sections 21 and28 connected in series and spaced apart, there being a projection 29 on the portion of the core leg which is between the coil sections. The two coil sections 21 and 28 on the right hand vertical leg are connected in bucking relation with the two coil sections 3! and 32 located on the left hand vertical leg 33. It will be understood that the two coil sections on a core leg may be connected either in series. or in parallel so long as their magnetic fields are in a direction to aid each other.

On the upper horizontal core leg 34, the two vertical deflecting coil sections 35 and 31 are connected with their fields in aiding relation while on the lower horizontal core leg 38 the vertical deflecting coil sections 39 and 4| are likewise connected with their magnetic fields in aiding relation. The connection of the vertical deflecting coils on the upper horizontal leg with respect to the vertical deflecting coils on the lower horizontal leg is such that the magnetic fields from the two horizontal legs 34 and 38 buck each other to form north and south poles on the vertical legs 26 and 33 as indicated by the letters N and S.

In addition to the increased sensitivity obtained by splitting the deflecting coils and providing core projections as illustrated in Fig. 4, there is a further advantage in this particular structure in that it provides a still more uniform magnetic field in the region of the cathode ray tube 9 both because of the core projections and because of the fact that the deflecting coils are split and spaced apart.

It will be evident that in addition to providing a deflecting structure which gives improved results I have provided a structure which is very simple in construction and which can be manufactured cheaply in quantity production.

From the foregoing description it will be apparent that various modifications may be made in my invention without departing from the spirit and scope thereof and I desire, therefore, that only such limitations shall be imposed thereon as are necessitated by the prior art and are set forth in the appended claims.

I claim as my invention:

1. In combination, a cathode ray tube, electromagnetic deflecting means for deflecting the cathode ray in said tube, saidmeans comprisinga closed magnetic core structure having a first pair of oppositely disposed legs and a second pair of oppositely disposed legs, a pair of de flecting coils wound on said first pair of core legs, said coils being connected with their magnetic; fields in bucking relation, to produce a deflecting field in the area surrounded by said core and with the deflecting field leaving one leg of said second pair and entering the other leg of said second pair, said second pair of core legs having opposing faces. of such contour as to produce a substantially uniform field in the region of the cathode ray being deflected, said core structure being so positioned that said deflecting field is substantially transverse to said cathode ray.

2. In combination, a cathode ray tube, electromagnetic deflecting means for deflecting the cathode ray in said tube, said means comprising a. closed magnetic core of rectangular shape, said core having two similar vertical legs and two similar horizontal legs, a pair of similar deflecting coils wound upon one pair of said similar legs and connected with their magnetic fields in bucking relation whereby a deflecting field is produced which is symmetrical with respect to the center of said core, the other pair of said similar legs having opposing faces. which are free of projections of suflicient length to concentrate the deflecting field in the region of the cathode ray being deflected whereby a substantially uniform field is produced in said region, said core struc-.,.

ture being so positioned that said deflecting field is substantially transverse to said cathode ray.

3. In combination, a cathode ray tube, electromagnetic deflecting meansfor deflecting the cathode ray in said tube, said means comprising a3. closed magnetic core structure of rectangular shape, said core structure having two similar vertical legs and two similar horizontal legs, a pair of similar deflecting coils wound upon a pair or" said similar legs and connected with theirv magnetic fields in bucking relation whereby a deflecting field is. produced which is symmetrical with respect to the center of said core, said core structure being so positioned that said deflecting field is substantially transverse to said cathode ray, and a second pair of similar deflecting coils wound upon the other pair of said similar legs and connected with the magnetic field of said second pair of coils in bucking relation.

4. In combination, a cathode ray tube, electroe 5.

magnetic deflecting means for deflecting the cathode ray in said tube, said means comprising a closed magnetic core structure of rectangular shape, said core structure having two similar vertical legs and two similar horizontal legs, a;

pair of similar deflecting coils wound upon a pair of said similar legs and connected with their magnetic fields in bucking relation whereby a deflecting field is produced which is symmetrical with respect to the center of said core, said core structure being so positioned that said deflecting field is substantially transverse to said cathode ray, each of said coils being split into two sections which are spaced apart, and the cor-e legs upon which said coils are wound having projec;;

tions which extend between said coil sections and towards the core center.

connected with their magnetic fields in bucking" relation, said two pairs of coils being so positioned with respect to each other that the deflecting field of one pair of coils is substantially at right angles to the deflecting field of the other pair of coils.

6. The invention according to claim 5 characterized in that each of said coils is split into a plurality of sections which are spaced apart.

'7. The invention according to claim 5 characterized in that each of said coils is split into a plurality of sections which are spaced apart, and further characterized in that projections extend from the core portions between said coil sections towards the center of said core structure, said projections being arranged symmetrically with respect to said center.

IOURY G. MALOF'F. 

